1. Field of the Invention
The present invention relates to an exposure head, an exposure apparatus, and application thereof, particularly relates to the exposure head which exposes a photosensitive material with a light beam modulated by a spatial light modulator according to image information, the exposure apparatus which inludes the exposure head, and a rapid prototyping apparatus, a stacking rapid prototyping apparatus, and a bleaching apparatus to which the exposure apparatus is applied, and a forming method of a micro channel which utilizes the exposure apparatus.
2. Description of the Related Art
Conventionally, there has been proposed various kinds of the exposure apparatus which performs an image exposure with the light beam modulated according to the image data, utilizing the spatial light modulator such as a digital micro-mirror device (DMD).
For example, DMD is a mirror device in which many micro-mirrors whose reflection plane angle is changeable according to a control signal are two-dimensionally arranged on a semiconductor substrate such as silicon, as shown in FIG. 15A, the exposure apparatus using DMD includes a light source 1 which applies a laser beam, a lens system 2 which collimates the laser beam emitted from the light source 1, DMD 3 which is arranged at an almost focal point of the lens system 2, and lens systems 4 and 6 which focuses the laser beam reflected with DMD 3 on a scanning surface 5.
In the above-described exposure apparatus, each of micro-mirrors in DMD 3 is on and off-controlled to modulate the laser beam by a control device which is not shown with a control signal generated according to the image data or the like, the image exposure is performed with the modulated laser beam.
However, DMD which is usually used is formed in such a manner that about 800 micro-mirrors in a main direction and about 600 micro-mirrors in a sub-scanning direction are two-dimensionally arranged on the substrate, it takes 10 to 200 μsec to modulate the laser beam by one micro-mirror corresponding to one pixel.
Therefore, for example, in the case that plural exposure heads arranged in the main direction is continuously moved in the sub-scanning direction, the modulation is performed at 200 μsec per one main scanning line, while the exposure head is moved by 2 μm in the sub-scanning direction, it takes about 50 seconds to expose an area of 50 mm2. That is to say, there is a problem that modulation speed of DMD is slow, so that it is difficult to perform the high-speed exposure in the exposure head using DMD as the spatial light modulator.
The invention has been done in order to solve the above-described problem, it is a first object of the invention to provide the exposure head and the exposure apparatus, in which the modulation speed of the spatial light modulator is increased and the high-speed exposure can be performed.
In recent years, as three-dimensional CAD (Computer Aided Design) system is widely spread, the rapid prototyping system is being utilized. The rapid prototyping system shapes a three-dimensional model in such a manner that a three-dimensional shape is formed in a virtual space on a computer with the three-dimensional CAD and the three-dimensional model is shaped on the basis of CAD data by exposing a photo-curable resin with the light beam. In the rapid prototyping system, on the computer, CAD data is sliced at a given interval to generate a plurality of section data, a surface of the liquid photo-curable resin is scanned on the basis of each section data with the laser beam and cured in laminar, the cured resin layer is stacked in order to shape the three-dimensional model. In the rapid prototyping method, a free liquid surface method is widely known, in which the photo-curable resin is reserved in an open-top type of tank, while a shaping table arranged near the liquid surface of the photo-curable resin is sequential descended from a free liquid surface, the cured resin layer is stacked.
Conventionally, in the rapid prototyping apparatus used for this rapid prototyping system, as described in “HIKARIZOUKEI SISUTEMU NO KISO, GENJOU, MONDAITEN, KATAGIJUTU” MARUYA, Yoji, Vol. 7, No. 10, pp. 18–23 (1992), there are the rapid prototyping apparatus adopting a laser plotter method scanning and the rapid prototyping apparatus adopting movable mirror method scanning.
FIG. 30 shows the rapid prototyping apparatus adopting the laser plotter method. In the apparatus, the laser beam oscillated from a laser light source 250 passes an optical fiber 254 including a shutter 252 and reaches an XY plotter 256, and the laser beam is applied from the XY plotter 256 to a liquid surface 266 of a photo-curable resin 262 in a vessel 260. Positions in an X-direction and a Y-direction of the XY plotter 256 are controlled with an XY positioning mechanism 258 including an X-positioning mechanism 258a and a Y-positioning mechanism 258b. Accordingly, while the XY plotter 256 is moved in the X-direction and Y-direction, the laser beam applied from the XY plotter 256 with the shutter 252 is on and off-controlled according to the section data, which allows the photo-curable resin 262 in a given portion of the liquid surface 266 to be cured.
However, in the rapid prototyping apparatus adopting the laser plotter method, there is the problem that shutter speed and moving speed of the plotter are limited and plenty time is required for the shaping.
FIG. 31 shows the rapid prototyping apparatus of the movable mirror method using a conventional galvanometer mirror. In the apparatus, the laser beam 270 is reflected with an X-axis rotating mirror 272 and a Y-axis rotating mirror 274 to be applied to the photo-curable resin 262. The X-axis rotating mirror 272 controls an irradiating position in the X-direction by rotating about a Z-axis, and the Y-axis rotating mirror 274 controls the irradiating position in the Y-direction by rotating about the X-axis. In the movable mirror method, the scanning speed can be increased compared with the laser plotter method.
However, in the rapid prototyping apparatus adopting the movable mirror method, since the scanning is performed with a micro laser spot, the shaping requires for long hours, for example, even in the case that the fast scanning of 2 to 12 m/s is peformed, it takes 8 to 24 hours to shape the three-dimensional model of about 10 centimeter cubic. The irradiation area of the laser beam 270 is limited, because the laser beam 270 is only reflected when the laser beam 270 is incident to the Y-axis rotating mirror 274 at a given range of the incident angle. In order to extend the irradiation range, when the Y-axis rotating mirror 274 is arranged at a higher position where the Y-axis rotating mirror 274 is far away from the photo-curable resin 262, there is the problem that a diameter of the laser spot is increased, positioning accuracy is worsened, and shaping accuracy is decreased. When rotating angle of the Y-axis rotating mirror 274 is increased, though the irradiation area is enlarged, the positioning accuracy is worsened in similar way, and a pin cushion error is increased. Furthermore, in the rapid prototyping apparatus using the galvanometer mirror, there is the problem that adjustment of the optical system is complicated and upsizing of the apparatus occurs because of the complicated optical system.
In rapid prototyping apparatuses of both methods, an ultraviolet laser beam having high output is used as the laser beam. In the related art, a gas laser such as an argon gas laser or a solid state laser generated by THG (Third Harmonic Wave) is usually used. However, in the gas laser, maintenance such as tube exchange is troublesome, incidental facilities such as cooling chiller which is expensive and raises the price of the rapid prototyping apparatus are required, and the apparatus is upsized. THG solid state gas laser is pulse operation of Q switch, repeating speed is slow and it is improper for the high-speed exposure. Since THG light is used, wavelength transformation efficiency is bad and high output is impossible. In addition, high output laser must be used as the exciting laser diode, it is very high cost.
In order to solve the problem, in Japanese Patent Application Laid-Open (JP-A) No. 11-138645, there is proposed the rapid prototyping apparatus in which a plurality of light sources which can irradiates the exposure region with larger spot size than single pixel are provided and the pixel is multi-exposed with the plurality of light sources. In the apparatus, since the pixel is exposed in multiple with the plurality of light sources, the output of each light source may be small, which enables cheap light emitting diode (LED) to use as the light source.
However, in the rapid prototyping apparatus described in JP-A No. 11-138645, there is the problem that, since the spot size of each light source is larger than the single pixel, the apparatus can not be used for the fine shaping, and, since the pixel is exposed in multiple with the plurality of light sources, there are many needless operations and the shaping requires long hours. Also, there is the problem that the exposure portion is upsized by increasing the number of light sources. Further, there is a fear that sufficient resolution is not obtained even if the multiple exposures are performed by the output light intensity (quantity of LED.
The invention has been done in order to solve the above-described problem, and it is a second object of the invention to provide the rapid prototyping apparatus which can perform the high-speed shaping. It is a third object of the invention to provide the rapid prototyping apparatus which can perform the fine shaping.
A powder sintering-stacking rapid prototyping apparatus is known as the rapid prototyping system which is developed after the stacking rapid prototyping apparatus using the photo-curable resin and widely used currently. In the powder sintering-stacking rapid prototyping apparatus, the surface of the powder body is scanned with the laser beam on the basis of the section data of the three-dimensional model which is generated on the computer. The powder body is cured in such a manner that the powder body is sequentially melted and sintered with the scanning of the laser beam, and the curing process is repeated. The three-dimensional model including the stacked sintered body is shaped by repeating the process.
In the stacking rapid prototyping apparatus adopting the sintering, there is an advantage that various kinds of materials can be selected, not only a ductile functional evaluation model or a precise casting pattern and a matrix but also a metal mold or a metallic part can be directly produced, and application field is wide. Further, in the stacking rapid prototyping apparatus, the apparatus price is moderate compared with the rapid prototyping apparatus, and forming speed is relatively fast, so that the application is fixing for confirmation of a design model.
However, even in the stacking rapid prototyping apparatus adopting the sintering, the movable mirror method such as the galvanometer mirror is adopted, and the gas laser such as CO2 laser (wavelength is 10.6 μm) and the solid state laser such as YAG laser (wavelength is 1.06 μm), which output the infrared having the high output power, are used as the light source. Therefore, the same problem as that of the above-desribed rapid prototyping apparatus occurs when these units is used. Since the beam spot is large, the resolution is low. Further, since the light source is long wavelength, a spread angle of the beam is large, so that sufficient focal depth can not be obtained.
The invention has been done in order to solve the above-described problem, and it is a fourth object of the invention to provide the rapid prototyping apparatus which can perform the high-speed shaping. It is a fifth object of the invention to provide the rapid prototyping apparatus which can perform the fine shaping.
Recently, a device technology called “lob on chip” (Laboratory on Chip), in which a system performing mixing, reaction, separation, and detection of a solution is integrated on a glass plate of several centimeters square, is actively investigated by adopting a micromachining technology. The lob on chip is also called as micro TAS (Micro Total Analysis System), micro reactor, or the like according to the integrated system.
Usually the lob on chip includes the micro channel whose channel width ranges from several tens μm to several hundreds μm, which is formed in the substrate having a thickness of about 1 mm. The mixing of the solution and the like is performed in the micro channel. Since relative area is enlarged in the micro channel, the mixing or reaction of the solution can be efficiently performed such that the solutions which hardly react with each other can react by a size effect and the solutions which are hardly mixed with each other can be mixed. By setting the channel width of the micro channel to the range form 10 μm to 50 μm, channel resistance can be relatively decreased and the good size effect can be obtained. Since the shape of the micro channel influences solution delivery characteristics, it is preferable that the micro channel has smooth wall surface and is produced finely.
Conventionally, the micro channel of the lob on chip is formed with a semiconductor processing technique such that the surface of the substrate is coated with a resist film, the resist film is patterned by photolithography with ultraviolet ray or electron beam, and then the substrate is etched by using the patterned resist film as a mask. The photolithography is performed with a contact aligner which is used in the semiconductor manufacturing process. Its exposure method is an analog exposure method which uses a mask aligner, for example, it is difficult to perform the fast exposure of a large area of 1 square meter.
In the forming method of the micro channel of the related art, since the patterning is performed with the mask exposure, there is the problem that the thickness of the photoresist film is limited, and it is difficult to finely form the micro channel. That is to say, when the photoresist film is thin, the photoresist film is easily side-etched in etching the substrate, preparation accuracy of the channel width is decreased, and sufficient channel depth can not be achieved.
In the mask exposure, since a precise glass mask or the like is required in each pattern, there is the product that cost is increased, it is difficult to enlarge the area, and it is not prefer to limited production of a wide variety of products.
On the other hand, though it is thought that the photolithography process is performed with a digital exposure method, the conventional digital exposure apparatus using the ultraviolet ray performs scanning exposure with the single beam, so that the exposure time is too long. In particular, in the case of the fine exposure in which the beam diameter is not more than 10 μm and addressability is about 1 μm, there is the problem that the exposure time is too long.
The invention has been done in order to solve the above-described problem, and it is a sixth object of the invention to provide the forming method of the micro channel which can finely form the micro channel at high speed. It is a seventh object of the invention to provide the forming method of the micro channel which can form the micro channel having an arbitrary pattern at low cost.
In dyeing of cloth product, bleaching in which color substance included in the cloth is dissolved and removed with oxidation or reduction treatment is performed prior to the dyeing. Though the color substance includes a conjugated double bond involving coloring in its structure, the conjugated system of the color substance is broken by the oxidation or reduction treatment, as a result, the cloth is bleached. A chlorine bleaching agent such as sodium hypochlorite, hydrogen peroxide, and the like are used as an oxidation bleaching agent. Hydrosulfite and the like are used as a reduction bleaching agent.
Conventionally, the above-described bleaching is usually performed by boiling the cloth product for long time in a water solution containing the dense bleaching agent, however, there is the problem that it is necessary that the water having large heat capacity is heated to near the boiling point, the energy efficiency is bad, embrittlement and hardening of the cloth, which are caused by interaction between the heat and the chemicals, are generated.
In recent years, research on the bleaching technique which does not use the chlorine bleaching agent having a large load to the environment is actively being done. For example, in JP-A No. 11-43861, there is disclosed a technique in which cotton cloth impregnated with sodium boron hydroxide is pulse-irradiated with the ultraviolet laser to bleach. Though reduction power of the sodium boron hydroxide, which is used as the bleaching agent, is weak, the color substance is activated with the laser irradiation to react easily with the bleaching agent. According to this technique, not only the bleaching can be performed without using the chlorine bleaching agent, but also the bleaching can be performed at lower temperature, so that the processing time can be reduced. Due to the bleaching at lower temperature, damage of the cloth is also reduced.
In the bleaching method, the laser device having the high energy density is required, and excimer laser which can obtain the high output in the ultraviolet region is used. Since the output of the laser diode which oscillates in the ultraviolet wave range is generaly small, when the laser diode is used, the plurality of laser diodes are integrated and used.
However, the energy efficiency of the excimer laser is as low as only 3%, and energy consumption is increased in the bleaching method using the excimer laser, so that the bleaching method is not environment-friendly. In the excimer laser, since repeating frequency of the pulse driving is as low as 300 Hz, the productivity is low. Further, there is also the problem that life of the laser tube or the laser gas is as low as about 1×107 shots, the maintenance cost is high, the apparatus is upsized, high-bright laser beam is not obtained, and pulse driving is difficult for the excimer laser.
Conventionally, the laser diode which oscillates in the ultraviolet wave range has not been realized, the specific construction of the laser diode is not described in JP-A No. 11-43861. In addition, though it is difficult to manufacture the laser diode having the short wavelength with high yield, in JP-A No. 11-43861, there is no description about the specific construction in which the plurality of laser diodes which oscillates in ultraviolet wave range are integrated and the light density of 10000 mJ/cm2 is realized and actually it is difficult to obtain the high output light source in which the laser diode oscillating in the ultraviolet wave range is used.
The invention has been done in order to solve the above-described problem of the related art, and it is an eighth object of the invention to provide the bleaching apparatus in which the bleaching can be performed with high energy density by applying the laser beam having the short pulse. It is a tenth object of the invention to provide the bleaching apparatus in which the energy efficiency is high and the fast and low-cost bleaching can be performed.